Report of the ASFA apheresis registry on muscle specific kinase antibody positive myasthenia gravis

Background: Anti-muscle specific kinase antibody positive (MuSK Ab) myasthenia gravis (MG) patients are known to have different clinical course compared to anti-acetylcholine receptor Ab positive MG patients. Therapeutic plasma exchange (TPE) has been reported to be effective; however, little is known of the response and of TPE procedural information. An ASFA Apheresis Registry was developed to analyze those data. Methods: The study collected detailed de-identified patient data, TPE procedures, and treatment outcome/complications. Collected data was described in aggregate. Results: A total of 15 MuSK Ab MG patients with exacerbation of MG symptoms, 13 females/2 males, median age 44, were investigated. Thirty TPE courses (median 5 procedures/course, total 145 procedures) were evaluated. All TPE procedures were performed with citrate anticoagulation, 1 − 1.25 plasma volume exchange in 100% fluid balance, and 90% of courses used only albumin as replacement. Calcium was added to albumin or given orally as needed. TPE was performed every other day in 55% of courses. Adverse events occurred in 3.4% of procedures. Ten patients (67%) experienced relapses within a median of 7 weeks. Objective symptoms were resolved in more than 75% of courses. Overall subjective improvement rates were 94.1%/93.3% after 3/4 TPE procedures, respectively. Thirty-one percent of patients responded poorly with minimal recovery. Conclusion: Overall subjective improvement was seen up to 94% of patients after one course of TPE. Some patients were poor-responders. Five TPE may be adequate for initial course with additional TPE as needed. Based upon this preliminary data, we will modify our future data collection. J. Clin. Apheresis, 2016. © 2016 Wiley Periodicals, Inc.